1. Field of the Invention
This invention relates to a two-dimensional visual display of light-emitting diodes to create dot-matrix, segmented character, bargraph and/or annunciator visual displays. Such displays are especially suited for the visual display output of aircraft instruments in the cockpit of aircraft.
2. Related Art
Visual aircraft instrument displays have previously included light-emitting diodes (e.g., for annunciator light outputs). However, a prior dot-matrix display for the STRIKEFINDER.RTM. atmospheric electrical discharge detector and display available from Insight Avionics Inc., uses a gas plasma display which has barely adequate brightness and a limited life. Other competitive instruments have used expensive CRT displays to obtain sufficient dot-matrix resolution.
A surface mounted light-emitting diode (LED) is also known and readily available commercially (e.g., from Lumex Corporation) with various different emitted colors of light (e.g., green, yellow, super yellow, red and super red). LED arrays have been made by applying chips to ceramic substrates and using wire bonding connections which are not too practical since microscopic bond wires are fragile and single chips are difficult to replace. However, conventional surface mounting techniques require a minimum sized surface bonding solder pad that extends beyond the edges of the surface mounted component by at least about 0.010 inch. For example, the recommended LED surface mount solder pad layout by Lumex Corporation would have solder pads extending outwardly end-to-end by 0.090 inch--for a surface mounted LED that is only 0.063 inch in total length (thus leaving 0.0135 inch of solder pad extending at each end beyond the LED itself). Such extended bonding solder pad layouts have conventionally been considered necessary so as to provide sufficient liquid solder meniscus to accurately center the surface mounted component at the desired location and/or for other reasons.
Perhaps for such reasons as these, it is not believed that surface mounted LEDs have previously been used to realize relatively dense dot-matrix or segmented character visual displays.